The Bible says many things about why the Israelites rejected Jesus, but in none of those places does it point the finger at unwritten traditions. The traditoins may have played a role, but seeking to be right with God through obedience to the law and refusal to place their faith in Jesus are the two things pointed to most often. Here are some esamples:
1 Brethren, my heart’s desire and prayer to God for Israel is that they may be saved. 2 For I bear them witness that they have a zeal for God, but not according to knowledge. 3 For they being ignorant of God’s righteousness, and seeking to establish their own righteousness, have not submitted to the righteousness of God. 4 For Christ is the end of the law for righteousness to everyone who believes. (Ro 10:1–4)
4 If anyone else thinks he may have confidence in the flesh, I more so: 5 circumcised the eighth day, of the stock of Israel, of the tribe of Benjamin, a Hebrew of the Hebrews; concerning the law, a Pharisee; 6 concerning zeal, persecuting the church; concerning the righteousness which is in the law, blameless. 7 But what things were gain to me, these I have counted loss for Christ. 8 Yet indeed I also count all things loss for the excellence of the knowledge of Christ Jesus my Lord, for whom I have suffered the loss of all things, and count them as rubbish, that I may gain Christ 9 and be found in Him, not having my own righteousness, which is from the law, but that which is through faith in Christ, the righteousness which is from God by faith; (Php 3:4–9)
19 You will say then, “Branches were broken off that I might be grafted in.” 20 Well said. Because of unbelief they were broken off, and you stand by faith. Do not be haughty, but fear. 21 For if God did not spare the natural branches, He may not spare you either. 22 Therefore consider the goodness and severity of God: on those who fell, severity; but toward you, goodness, if you continue in His goodness. Otherwise you also will be cut off. 23 And they also, if they do not continue in unbelief, will be grafted in, for God is able to graft them in again. (Ro 11:19–23)